Dans right it is a nodule and could contain a fossil but not a cannon ball nodule, cannon ball nodules (Jurassic) come from bed 33 cannon ball doggers near Whitby but are found on the Holderness because of the last ice age and rocks and fossils being transported inside glaziers and deposited when they melted.

I have found similar nodules that contained coprolites and looking at the matrix could have come from Speeton (Cretaceous) but it's hard to tell.

It is a concretion. That word covers a range of different types of object, but they are all the result of local chemical changes (sometimes with physical changes) in the rock.

Think of rain drops as an analogy. Given supersaturated air, water will try to condense out of it, and it will start to do so using particles of dust/pollen/etc as a nucleus. Once a rain drop has formed, the air around it will be less saturated; the system will be in better equilibrium, so the raindrop will persist.

Back to the rock: Since the sediment was deposited and turned to rock (or at least since the sequence of events leading up to rock had begun), the physical and chemical environment changed, for instance due to burial by other sediment and/or by heating. That state of disequilibrium caused chemical and physical processes to rearrange the material comprising the rock (minerals/molecules/elements being altered and moved). Such changes often use fossils as a nucleus, growing outwards and enveloping the nucleus in a volume of rock of somewhat different chemistry. That, in outline, is a concretion. A concretion may grade gradually into the surrounding rock, or it may, as in your example, be relatively distinct (and hence physically separable). They can also show concentric layering, which you can see to a small extent in yours: there is a bluish-grey halo around the discrete concretion.

Although the words concretion and nodule are often used somewhat interchangeably,

"There is an important distinction to draw between concretions and nodules. Concretions are formed from mineral precipitation around some kind of nucleus while a nodule is a replacement body."

(from the link below)

Canonball concretions are a common name for these things in some places. There are many other common names. Bowling Ball Beach in California gets its name from the conretions on the shore (see the first photo here - http://en.wikipedia.org/wiki/Concretion).

Your example looks a bit like what are called Moqui marbles in Utah (see same link)

Some types of concretion have mineral veins dividing them into numerous chunks. These are called septarian concretions (commonly also septarian nodules, which is less correct). There is a hint of that in your specimen - note the short pale mineral veins (probably calcite or quartz).

Septarian concretions are also discussed in that link.

I can't see a fossil at the core of your concretion. It may still be within it, or it could be too small to see unaided, or something else might have acted as the nucleus (eg. an particular mineral grain), or there may simply not have been an obvious nucleus.

Your second image is an ammonite called Kosmoceras from the Callovian of the Middle Jurassic, i have found a few of these but the sediment has not really formed into rock and is very fragile when the specimen has dried out, so you have to be very carefull with it.

Nearly forgot Nobby I have split my 'egg' tonight and although i was dissapointed there did not look to be anything inside when i took a closer look i could see a fossil, probably a gastropod about 2mm across.

Sorry to go on Nobby but don't just look for fossils were you find the pyritic ammonites, as I said things of a similar density settle in one place especially artifacts that have washed out of the boulder clay.

It's great to get some feedback thanks tabfish. We generally don't look on the ground. All our finds mainly come direct from the boulder clay face. We like to go after a storm if we can to there's a fresh face to scour.

Forgot to add under the sand on the beach is far more boulder clay than in the face of the cliff, so when the beach is stripped of sand and you are walking on the clay keep your 'eyes out' if you know what I meen.